Methacrylic resins including a crosslinked elastic body and having excellent transparency, weatherability, hardness, and shock resistance are generally used with an ultraviolet absorber mixed therein. Especially, when it is used as a film, a large amount of an ultraviolet absorber has to be added as the thickness of the film becomes thinner.
Thus, when the film is formed by a method such as extrusion, there have been problems such as extruder's vent clogging, T-die's gum sticking, and chill roll's whitening, and when a further amount has to be added, there have been problems such as a rough film surface and elution (bleed out) to the film surface.
Even though a large amount of an ultraviolet absorber could be added to methacrylic resin compositions, since a general ultraviolet absorber has a poor compatibility with methacrylic resins and a low molecular weight, there is a problem in that the absorber is partially volatilized at the time of the extrusion, failing to bring out the ultraviolet-shielding characteristics. Also, since the ultraviolet absorber is released from methacrylic resin composition under a long-term usage, there is a problem in that the ultraviolet-shielding characteristics decrease over time. Further, when the methacrylic resin film is layered on a molded article comprising a PVC resin composition containing a plasticizer, since the plasticizer in the PVC resin permeates the methacrylic resin film and passes through to elute (bleed out), the elution (bleed out) of the ultraviolet absorber in the methacrylic resin film has been accelerated.
A generally known method for solving these problems is to select and add a particular ultraviolet absorber. However, in the method of simply adding a particular ultraviolet absorber, the added ultraviolet absorber in the obtained film is eluted (bleed out) when soaked with warm water and exposed to outdoors, and the problems such as a decline in ultraviolet-shielding characteristics and whitening are yet to be solved.
For such problems, there has been proposed a method in which a particular monomer showing ultraviolet absorbency is copolymerized with methacrylic resin (Patent Publication Documents 1 to 4). Although Patent Publication Documents 1 and 2 note copolymerizing an ultraviolet absorber represented by the general formula (1), it was not a polymer including a crosslinked elastic particle, and there still were problems of bending-fracturing resistance in its usage as a film. On the other hand, although Patent Publication Documents 3 and 4 disclose a film comprising a polymer including a crosslinked elastic particle, bending-fracturing resistance, and moldability (thinning of film) were unsatisfactory.
[Patent Publication Document 1] JP 60-38411 A
[Patent Publication Document 2] JP 05-255447 A
[Patent Publication Document 3] JP 09-194542 A
[Patent Publication Document 4] JP 08-319326 A